This application claims the priority of German patent 197 54 959.4, filed Dec. 11, 1997, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a motor vehicle wheel having hollow spokes and more particularly to such a wheel made of light metal and producible in a casting operation.
From German Patent Document DE 44 21 470 A1, a cast vehicle wheel having hollow spokes is known which have an opening in the rim for removing a core, and the space of the wheel from which the core was removed forms a hollow space which is open toward the rim.
Furthermore, from German Patent Document DE 19 501 508, components are known for a chassis of a motor vehicle which consist of diecast aluminum and have a hollow space in which the aluminum foam is situated.
It is an object of the invention to provide a vehicle wheel having hollow spokes which can be produced in a simple manner and which has a stable construction.
This and other objects have been achieved according to the present invention by providing a motor vehicle wheel having hollow spokes made of a light metal and producible in a casting operation, each of said spokes having a dead core made of a metallic material in a hollow space, said dead core forming a closed hollow space in the spoke.
This and other objects have been achieved according to the present invention by providing a cast motor vehicle wheel, comprising: a cast rim; a cast wheel spider having a plurality of spokes; and a non-cast core located in each of said spokes, said core being unremovable from said spokes.
This and other objects have been achieved according to the present invention by providing a method of making a motor vehicle wheel, comprising: providing a casting die having die spaces defining a rim and a wheel spider having a plurality of spokes; positioning a core in each of said die spaces defining said spokes; and providing a casting material to said die spaces such that said core is embedded within said casting material, said core being unremovable from said spokes.
The principal advantages achieved by the invention are that the hollow spaces (i.e., core spaces) of the wheel spokes promote the dimensional stability of the wheel spokes via a dead core consisting either of at least one shell or a metal foam. As the resup of the dead core, a lower wall thickness of the wheel spokes can be selected, whereby the wheel as a whole becomes lighter than a wheel with unfilled hollow spaces.
The dead core must be arranged in a precise position in the casting die by way of positioning elements, such as pins, so that a dimensional precision can be achieved as with a sand core. So that any finishing is eliminated, the positioning elements consist of a light metal, like the wheel, so that an intimate connection with the spoke wall takes place during the casting process. The dead core may also be arranged in the areas between the wheel spokes in the rim.
The shell-shaped hollow elements may consist of metals, such as a light metal, for example, of an aluminum alloy or of a steel alloy; other metals also being contemplated which have a melting point above the casting temperature.
The hollow elements may also be composed of several shells and may be produced in a hydroformed manner.
The foamed core consisting, for example, of aluminum has a correspondingly treated skin. The core should have a considerably lower overall density than the casting material. Furthermore, for the space of the casting operation, the core must be resistant the temperature of the molten mass and dimensionally stable for the duration of the casting operation.
Among other advantages, the use of dead cores results in the advantage that molding sand need not be shaken out of the hollow spaces.
Various supports of the dead core are contemplated for the casting of the wheel. Thus, the dead core can be supported in the wheel hub. Furthermore, a support in the bores of the wheel bolts is contemplated. Also, a support can take place through openings in the rim. The dead core is a cohesive structure and fills all hollow spaces of the wheel, such as the spokes and the annuli.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.